The analysis of a particular component in blood is widely performed to check the condition of a human body. In recent years, such analysis of a particular component is performed using a relatively compact analyzer instead of using a large apparatus. To reduce the size of such an analyzer, the flow path in the analyzer needs to be made as small as possible, and a technique is necessary to properly feed blood or other kind of liquid through the flow path.
FIG. 40 shows an example of liquid feeder for a conventional liquid feeding method. The liquid feeder X shown in the figure includes an analysis portion 91, a heater 92, a minute flow path 93, a plurality of valves 94 and a liquid pooling tank 95. The heater 92 heats blood or other kind of liquid. The heated liquid is injected into an introduction port 93i of the minute flow path 93 shown in the left side in the figure. In flowing through the minute flow path 93 or the liquid pooling tank 95, the liquid may be diluted to a concentration suitable for the analysis or mixed with a reagent. The sample liquid obtained by such dilution or mixing is fed into the analysis portion 91 through a discharge port 93o. In the analysis portion 91, the analysis of a particular component by e.g. optical means is performed. The sample liquid after the analysis is introduced again into the minute flow path 93 thorough the introduction port 93i shown in the right side in the figure and then discharged to e.g. a non-illustrated drain. In the liquid feeder X, the start and stop of the liquid feeding in the minute flow path 93 and the selection of the liquid feeding direction from a branch portion are performed by utilizing the valves 94 provided in the minute flow path 93 along the flow direction. Each of the valves 94 is rotatable and switched between a closed state, an open state and a state to control the liquid flow to a certain direction by a rotation drive means (not shown) provided in the analyzer X. Thus, by properly arranging the valves 94 in the minute flow path 93, the liquid is fed in a desired direction.
When the system for analyzing e.g. blood is made up of an analyzer and a cartridge to be mounted to the analyzer, the minute flow path 93 and the valves 94 need to be provided in the cartridge. The provision of the valves 94, which are rotatable parts, complicates the structure of the cartridge. Particularly, since the leakage of blood or other kind of liquid from the slidable portions of the valves 94 needs to be prevented, the manufacturing of the cartridge is difficult. Further, to reduce the size of such a cartridge is difficult. To frequently perform the analysis of a particular component in blood conveniently, the size reduction of a cartridge is essential. Further, since the above-described analyzer requires the rotation drive means for rotating the valves 94, the structure of the analyzer is complicated and the size is increased.    Patent Document 1: U.S. Pat. No. 4,624,928